Although Ziegler-Natta polyolefin catalyst is originated in the 1950s, but so far it is still the main catalyst used for olefin polymerization. After continuous innovation and development, Ziegler-Natta catalyst which initially mainly consisted of TiCl3/AlEt2Cl-based now developed to mainly consist of IVB˜VB group metal compounds (for example: titanium or vanadium compounds and so on), magnesium halide and at least one electron donor component, such system is effective which play a important role in industrial application and research. Regardless of its application in polymerization in ethylene or propylene, people are constantly improving the productivity and the catalytic performance of the catalyst in order to produce a higher performance polymer resin and reduce energy consumption at the same time.
After numerous studies had been done about the catalyst composition, it is found that the catalytic performance is greatly affected by the catalyst support. The support is not only the dispersant which dispersed the catalyst active site; such dispersant can maximize the catalytic activity, but also the template for polymer growing. The stability and continuity of polymer production is decided by the particle morphology, size, distribution, strength and so on, especially for the gas phase and slurry method, which had been proved by many production practice and research.
Presently, in olefin polymerization catalyst preparation, the method of dispersing catalyst active site is generally as following: (1) support, i.e., catalyst composition is supported on the formed support physically or chemically, such formed support generally is magnesium chloride, silica, alumina, diatomite and other inert inorganic materials, cross-linked polystyrene and other organic substance; (2) the active site is dispersed on magnesium chloride support by co-precipitation of catalyst composition and magnesium chloride, such as the preparation of olefin polymerization catalyst in U.S. Pat. No. 4,354,009; (3)dispersing the active site by spray drying catalyst composition and an inert inorganic material which has very small average size and plays as dispersant together, such as disclosed in U.S. Pat. Nos. 7,276,566, 7,160,833, 6,982,237, 6,806,221, and many other U.S. patents. The above methods used single material as catalyst support or dispersant, and polyethylene with narrow molecular weight distribution and fusion flow ratio generally of 30 or less will be produced when Z-N catalysts according to the above methods are used in ethylene polymerization.
An important way to develop novel support is loading polyolefin catalyst on inorganic/organic composite support. The activity and selectivity of catalyst, and polymer properties can be adjusted owing to the diversity of the functional group on the organic support. Presently, the main research about inorganic/organic composite support focused on improving the activity of catalyst; properties and morphology of polymer by adjusting the support. As indicated in Sukhdeep Kaur, etc. Mg (OEt)2 and benzyl chloride is reacted together to get MgCl2.xEB solid, said MgCl2.xEB solid is added into homogenous chlorobenzene solution of the copolymer of methacrylic acid and 1-octene to get mixed liquid of MgCl2.xEB/Poly(methyl acrylate-co-1-octene), and catalyst with TiCl4 supported on composite support will be obtained by reacting said mixed liquid with TiCl4 after drying later. Polyethylene with broad molecular weight distribution can be produced by using said catalyst.